Up to now, an adhesive containing an epoxy resin, as a thermosetting resin, has been used for connecting a semiconductor chip to a substrate, and for connecting a TCP (tape carrier package) to an LCD (liquid crystal display) to manufacture an electrical appliance. This adhesive is cured by thermal polymerization of an epoxy resin.
For accelerating the thermal polymerization reaction, a latent curing agent is added to the adhesive. This sort of the latent curing agent is shown in FIG. 1. A latent curing agent 130, shown in FIG. 1, includes a core member 131 formed by a particulate curing agent (a fine particle of a curing agent) and a capsule 137 which covers up the surface of the core member 131. When the latent curing agent is mixed with an epoxy resin to prepare an adhesive, the curing agent, which forms the core member 131, and the epoxy resin in the adhesive, are separated from each other by the capsule 137, at ambient temperature, so that there occurs no polymerization reaction of the epoxy resin. The capsule 137 is formed by a thermoplastic resin, such as urethane resin, and, if the adhesive is heated to a temperature higher than a predetermined temperature, the capsule 137 is fused or destroyed by thermal deformation, so that the core member 131 is ejected into the adhesive. When the adhesive is continuously heated in this state, the polymerization reaction of the epoxy resin proceeds rapidly, by the curing agent forming the core member 131, thus curing the adhesive.
By using the above-described latent curing agent 130, it is possible to produce an adhesive which is superior in preservability on storage at ambient temperature and which exhibits a high curing performance on heating.
However, the above-described particulate curing agent is more difficult to undergo dispersion into an adhesive than the liquid curing agent, such that the polymerization reaction of the epoxy resin proceeds more slowly than in case of using a liquid curing agent.
As the curing agent, forming the core member 131, a modified amine compound, for example, is generally employed. However, in polymerizing the epoxy resin using such curing agent, the adhesive needs to be heated to equal to or higher than 180° C., such that there is a risk of thermal deformation of the components to be bonded together. Although this problem may be overcome by using a lower heating temperature, the time needed for heating processing is prolonged, thus worsening the productivity.